£300,000 mortgage: monthly payments

By The PocketSums team. Updated 30 September 2026. How we calculate

Borrowing £300,000? At 4.5% over 25 years you would pay £1,667.50 a month. Every rate and term is compared below.

At 4.5% over 25 years
£1,668 a month
Total interest
£200,250
Income needed (4.5x)
£66,667
Overpay £150 a month
save £31,714
£270,000 mortgage£280,000 mortgage£290,000 mortgage£310,000 mortgage
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Monthly payment£1,667.50a month

Borrowing £300,000 (90% loan to value). Total repaid £500,250, of which £200,250 is interest.

A £300,000 repayment mortgage at 4.5% over 25 years costs £1,667.50 a month. You would repay £500,250 in total, of which £200,250 is interest.

Monthly payments on £300,000 by rate and term

Rate 20 years 25 years 30 years 35 years
3.5% £1,740 £1,502 £1,347 £1,240
4% £1,818 £1,584 £1,432 £1,328
4.5% £1,898 £1,668 £1,520 £1,420
5% £1,980 £1,754 £1,610 £1,514
5.5% £2,064 £1,842 £1,703 £1,611
6% £2,149 £1,933 £1,799 £1,711

How £300,000 is paid off over 25 years

£0k£50k£100k£150k£200k£250k£300k0y5y10y15y20y25y
  • Balance still owed
  • Interest paid so far
At 4.5%. Interest is heaviest in the early years, when the balance is highest.

Total interest on £300,000 by term

  1. 20 years£155,508 (£1,898 a month)
  2. 25 years£200,250 (£1,668 a month)
  3. 30 years£247,222 (£1,520 a month)
  4. 35 years£296,303 (£1,420 a month)

A longer term lowers the monthly payment but adds interest. Stretching from 25 to 35 years saves £248 a month and costs £96,053 more overall.

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Questions people ask

What are the monthly payments on a £300,000 mortgage?

£1,667.50 a month on a 25 year repayment mortgage at 4.5%. At 4% it is £1,583.51 and at 5% it is £1,753.77. Interest only at 4.5% would be £1,125.00.

What salary do I need for a £300,000 mortgage?

At the usual 4.5 times income, about £66,667 for a single buyer or a joint household income. Some lenders go to 5 or 5.5 times, which would need around £54,545.

How much does overpaying a £300,000 mortgage save?

Paying £150 extra a month at 4.5% clears it about 3 years 6 months early and saves roughly £31,714 in interest. Check your lender's overpayment limit, often 10% a year on fixed deals.